What's the coolest use for a video projector?

For me, it is using it to project visualization patterns from my computer during a house party disco. I have also read on this forum about the use of a video projector for an outdoor "drive-in style" movie experience!

A bit "normal" but I made a video of my nephew's wedding and projected it on a big white wall at the reception disco. The DJ was really good at playing tracks that matched the video and it was well received.